516 lines
20 KiB
C
Executable File
516 lines
20 KiB
C
Executable File
/* Arduino SoftI2C library.
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*
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* This is a very fast and very light-weight software I2C-master library
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* written in assembler. It is based on Peter Fleury's I2C software
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* library: http://homepage.hispeed.ch/peterfleury/avr-software.html
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*
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*
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* This Library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This Library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with the Arduino I2cMaster Library. If not, see
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* <http://www.gnu.org/licenses/>.
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*/
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/* In order to use the library, you need to define SDA_PIN, SCL_PIN,
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* SDA_PORT and SCL_PORT before including this file. Have a look at
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* http://www.arduino.cc/en/Reference/PortManipulation for finding out
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* which values to use. For example, if you use digital pin 3 for
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* SDA and digital pin 13 for SCL you have to use the following
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* definitions:
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* #define SDA_PIN 3
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* #define SDA_PORT PORTB
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* #define SCL_PIN 5
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* #define SCL_PORT PORTB
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*
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* You can also define the following constants (see also below):
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* - I2C_CPUFREQ, when changing CPU clock frequency dynamically
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* - I2C_FASTMODE = 1 meaning that the I2C bus allows speeds up to 400 kHz
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* - I2C_SLOWMODE = 1 meaning that the I2C bus will allow only up to 25 kHz
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* - I2C_NOINTERRUPT = 1 in order to prohibit interrupts while
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* communicating (see below). This can be useful if you use the library
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* for communicationg with SMbus devices, which have timeouts.
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* Note, however, that interrupts are disabledfrom issuing a start condition
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* until issuing a stop condition. So use this option with care!
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* - I2C_TIMEOUT = 0..10000 mssec in order to return from the I2C functions
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* in case of a I2C bus lockup (i.e., SCL constantly low). 0 means no timeout
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*/
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/* Changelog:
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* Version 1.1:
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* - removed I2C_CLOCK_STRETCHING
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* - added I2C_TIMEOUT time in msec (0..10000) until timeout or 0 if no timeout
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* - changed i2c_init to return true iff both SDA and SCL are high
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* - changed interrupt disabling so that the previous IRQ state is retored
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* Version 1.0: basic functionality
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*/
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#include <avr/io.h>
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#include <Arduino.h>
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#ifndef _SOFTI2C_H
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#define _SOFTI2C_H 1
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#if defined (__AVR__)
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// Init function. Needs to be called once in the beginning.
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// Returns false if SDA or SCL are low, which probably means
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// a I2C bus lockup or that the lines are not pulled up.
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boolean __attribute__ ((noinline)) i2c_init(void);
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// Start transfer function: <addr> is the 8-bit I2C address (including the R/W
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// bit).
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// Return: true if the slave replies with an "acknowledge", false otherwise
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bool __attribute__ ((noinline)) i2c_start(uint8_t addr);
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// Similar to start function, but wait for an ACK! Be careful, this can
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// result in an infinite loop!
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void __attribute__ ((noinline)) i2c_start_wait(uint8_t addr);
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// Repeated start function: After having claimed the bus with a start condition,
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// you can address another or the same chip again without an intervening
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// stop condition.
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// Return: true if the slave replies with an "acknowledge", false otherwise
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bool __attribute__ ((noinline)) i2c_rep_start(uint8_t addr);
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// Issue a stop condition, freeing the bus.
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void __attribute__ ((noinline)) i2c_stop(void) asm("ass_i2c_stop");
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// Write one byte to the slave chip that had been addressed
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// by the previous start call. <value> is the byte to be sent.
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// Return: true if the slave replies with an "acknowledge", false otherwise
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bool __attribute__ ((noinline)) i2c_write(uint8_t value) asm("ass_i2c_write");
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// Read one byte. If <last> is true, we send a NAK after having received
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// the byte in order to terminate the read sequence.
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uint8_t __attribute__ ((noinline)) i2c_read(bool last);
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// You can set I2C_CPUFREQ independently of F_CPU if you
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// change the CPU frequency on the fly. If do not define it,
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// it will use the value of F_CPU
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#ifndef I2C_CPUFREQ
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#define I2C_CPUFREQ F_CPU
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#endif
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// If I2C_FASTMODE is set to 1, then the highest possible frequency below 400kHz
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// is selected. Be aware that not all slave chips may be able to deal with that!
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#ifndef I2C_FASTMODE
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#define I2C_FASTMODE 0
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#endif
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// If I2C_FASTMODE is not defined or defined to be 0, then you can set
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// I2C_SLOWMODE to 1. In this case, the I2C frequency will not be higher
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// than 25KHz. This could be useful for problematic buses.
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#ifndef I2C_SLOWMODE
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#define I2C_SLOWMODE 0
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#endif
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// if I2C_NOINTERRUPT is 1, then the I2C routines are not interruptable.
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// This is most probably only necessary if you are using a 1MHz system clock,
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// you are communicating with a SMBus device, and you want to avoid timeouts.
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// Be aware that the interrupt bit is enabled after each call. So the
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// I2C functions should not be called in interrupt routines or critical regions.
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#ifndef I2C_NOINTERRUPT
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#define I2C_NOINTERRUPT 0
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#endif
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// I2C_TIMEOUT can be set to a value between 1 and 10000.
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// If it is defined and nonzero, it leads to a timeout if the
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// SCL is low longer than I2C_TIMEOUT milliseconds, i.e., max timeout is 10 sec
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#ifndef I2C_TIMEOUT
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#define I2C_TIMEOUT 0
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#else
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#if I2C_TIMEOUT > 10000
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#error I2C_TIMEOUT is too large
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#endif
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#endif
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#define I2C_TIMEOUT_DELAY_LOOPS (I2C_CPUFREQ/1000UL)*I2C_TIMEOUT/4000UL
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#if I2C_TIMEOUT_DELAY_LOOPS < 1
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#define I2C_MAX_STRETCH 1
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#else
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#if I2C_TIMEOUT_DELAY_LOOPS > 60000UL
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#define I2C_MAX_STRETCH 60000UL
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#else
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#define I2C_MAX_STRETCH I2C_TIMEOUT_DELAY_LOOPS
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#endif
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#endif
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#if I2C_FASTMODE
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#define I2C_DELAY_COUNTER (((I2C_CPUFREQ/400000L)/2-19)/3)
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#else
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#if I2C_SLOWMODE
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#define I2C_DELAY_COUNTER (((I2C_CPUFREQ/25000L)/2-19)/3)
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#else
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#define I2C_DELAY_COUNTER (((I2C_CPUFREQ/100000L)/2-19)/3)
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#endif
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#endif
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// Table of I2C bus speed in kbit/sec:
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// CPU clock: 1MHz 2MHz 4MHz 8MHz 16MHz 20MHz
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// Fast I2C mode 40 80 150 300 400 400
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// Standard I2C mode 40 80 100 100 100 100
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// Slow I2C mode 25 25 25 25 25 25
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// constants for reading & writing
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#define I2C_READ 1
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#define I2C_WRITE 0
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// map the IO register back into the IO address space
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#define SDA_DDR (_SFR_IO_ADDR(SDA_PORT) - 1)
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#define SCL_DDR (_SFR_IO_ADDR(SCL_PORT) - 1)
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#define SDA_OUT _SFR_IO_ADDR(SDA_PORT)
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#define SCL_OUT _SFR_IO_ADDR(SCL_PORT)
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#define SDA_IN (_SFR_IO_ADDR(SDA_PORT) - 2)
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#define SCL_IN (_SFR_IO_ADDR(SCL_PORT) - 2)
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#ifndef __tmp_reg__
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#define __tmp_reg__ 0
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#endif
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// Internal delay functions.
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void __attribute__ ((noinline)) i2c_delay_half(void) asm("ass_i2c_delay_half");
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void __attribute__ ((noinline)) i2c_wait_scl_high(void) asm("ass_i2c_wait_scl_high");
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void i2c_delay_half(void)
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{ // function call 3 cycles => 3C
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#if I2C_DELAY_COUNTER < 1
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__asm__ __volatile__ (" ret");
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// 7 cycles for call and return
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#else
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__asm__ __volatile__
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(
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" ldi r25, %[DELAY] ;load delay constant ;; 4C \n\t"
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"_Lidelay: \n\t"
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" dec r25 ;decrement counter ;; 4C+xC \n\t"
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" brne _Lidelay ;;5C+(x-1)2C+xC\n\t"
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" ret ;; 9C+(x-1)2C+xC = 7C+xC"
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: : [DELAY] "M" I2C_DELAY_COUNTER : "r25");
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// 7 cycles + 3 times x cycles
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#endif
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}
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void i2c_wait_scl_high(void)
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{
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#if I2C_TIMEOUT <= 0
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__asm__ __volatile__
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("_Li2c_wait_stretch: \n\t"
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" sbis %[SCLIN],%[SCLPIN] ;wait for SCL high \n\t"
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" rjmp _Li2c_wait_stretch \n\t"
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" cln ;signal: no timeout \n\t"
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" ret "
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: : [SCLIN] "I" (SCL_IN), [SCLPIN] "I" (SCL_PIN));
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#else
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__asm__ __volatile__
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( " ldi r27, %[HISTRETCH] ;load delay counter \n\t"
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" ldi r26, %[LOSTRETCH] \n\t"
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"_Lwait_stretch: \n\t"
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" clr __tmp_reg__ ;do next loop 255 times \n\t"
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"_Lwait_stretch_inner_loop: \n\t"
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" rcall _Lcheck_scl_level ;call check function ;; 12C \n\t"
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" brpl _Lstretch_done ;done if N=0 ;; +1 = 13C\n\t"
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" dec __tmp_reg__ ;dec inner loop counter;; +1 = 14C\n\t"
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" brne _Lwait_stretch_inner_loop ;; +2 = 16C\n\t"
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" sbiw r26,1 ;dec outer loop counter \n\t"
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" brne _Lwait_stretch ;continue with outer loop \n\t"
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" sen ;timeout -> set N-bit=1 \n\t"
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" rjmp _Lwait_return ;and return with N=1\n\t"
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"_Lstretch_done: ;SCL=1 sensed \n\t"
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" cln ;OK -> clear N-bit \n\t"
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" rjmp _Lwait_return ; and return with N=0 \n\t"
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"_Lcheck_scl_level: ;; call = 3C\n\t"
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" cln ;; +1C = 4C \n\t"
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" sbic %[SCLIN],%[SCLPIN] ;skip if SCL still low ;; +2C = 6C \n\t"
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" rjmp _Lscl_high ;; +0C = 6C \n\t"
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" sen ;; +1 = 7C\n\t "
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"_Lscl_high: "
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" nop ;; +1C = 8C \n\t"
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" ret ;return N-Bit=1 if low ;; +4 = 12C\n\t"
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"_Lwait_return:"
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: : [SCLIN] "I" (SCL_IN), [SCLPIN] "I" (SCL_PIN),
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[HISTRETCH] "M" (I2C_MAX_STRETCH>>8),
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[LOSTRETCH] "M" (I2C_MAX_STRETCH&0xFF)
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: "r26", "r27");
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#endif
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}
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boolean i2c_init(void)
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{
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__asm__ __volatile__
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(" cbi %[SDADDR],%[SDAPIN] ;release SDA \n\t"
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" cbi %[SCLDDR],%[SCLPIN] ;release SCL \n\t"
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" cbi %[SDAOUT],%[SDAPIN] ;clear SDA output value \n\t"
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" cbi %[SCLOUT],%[SCLPIN] ;clear SCL output value \n\t"
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" clr r24 ;set return value to false \n\t"
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" clr r25 ;set return value to false \n\t"
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" sbis %[SDAIN],%[SDAPIN] ;check for SDA high\n\t"
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" ret ;if low return with false \n\t"
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" sbis %[SCLIN],%[SCLPIN] ;check for SCL high \n\t"
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" ret ;if low return with false \n\t"
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" ldi r24,1 ;set return value to true \n\t"
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" ret "
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: :
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[SCLDDR] "I" (SCL_DDR), [SCLPIN] "I" (SCL_PIN),
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[SCLIN] "I" (SCL_IN), [SCLOUT] "I" (SCL_OUT),
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[SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN),
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[SDAIN] "I" (SDA_IN), [SDAOUT] "I" (SDA_OUT));
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return true;
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}
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bool i2c_start(uint8_t addr)
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{
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__asm__ __volatile__
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(
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#if I2C_NOINTERRUPT
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" cli ;clear IRQ bit \n\t"
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#endif
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" sbis %[SCLIN],%[SCLPIN] ;check for clock stretching slave\n\t"
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" rcall ass_i2c_wait_scl_high ;wait until SCL=H\n\t"
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" sbi %[SDADDR],%[SDAPIN] ;force SDA low \n\t"
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" rcall ass_i2c_delay_half ;wait T/2 \n\t"
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" rcall ass_i2c_write ;now write address \n\t"
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" ret"
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: : [SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN),
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[SCLIN] "I" (SCL_IN),[SCLPIN] "I" (SCL_PIN));
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return true; // we never return here!
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}
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bool i2c_rep_start(uint8_t addr)
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{
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__asm__ __volatile__
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(
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#if I2C_NOINTERRUPT
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" cli \n\t"
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#endif
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" sbi %[SCLDDR],%[SCLPIN] ;force SCL low \n\t"
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" rcall ass_i2c_delay_half ;delay T/2 \n\t"
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" cbi %[SDADDR],%[SDAPIN] ;release SDA \n\t"
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" rcall ass_i2c_delay_half ;delay T/2 \n\t"
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" cbi %[SCLDDR],%[SCLPIN] ;release SCL \n\t"
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" rcall ass_i2c_delay_half ;delay T/2 \n\t"
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" sbis %[SCLIN],%[SCLPIN] ;check for clock stretching slave\n\t"
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" rcall ass_i2c_wait_scl_high ;wait until SCL=H\n\t"
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" sbi %[SDADDR],%[SDAPIN] ;force SDA low \n\t"
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" rcall ass_i2c_delay_half ;delay T/2 \n\t"
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" rcall ass_i2c_write \n\t"
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" ret"
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: : [SCLDDR] "I" (SCL_DDR), [SCLPIN] "I" (SCL_PIN),[SCLIN] "I" (SCL_IN),
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[SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN));
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return true; // just to fool the compiler
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}
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void i2c_start_wait(uint8_t addr)
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{
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__asm__ __volatile__
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(
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" push r24 ;save original parameter \n\t"
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"_Li2c_start_wait1: \n\t"
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" pop r24 ;restore original parameter\n\t"
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" push r24 ;and save again \n\t"
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#if I2C_NOINTERRUPT
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" cli ;disable interrupts \n\t"
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#endif
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" sbis %[SCLIN],%[SCLPIN] ;check for clock stretching slave\n\t"
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" rcall ass_i2c_wait_scl_high ;wait until SCL=H\n\t"
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" sbi %[SDADDR],%[SDAPIN] ;force SDA low \n\t"
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" rcall ass_i2c_delay_half ;delay T/2 \n\t"
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" rcall ass_i2c_write ;write address \n\t"
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" tst r24 ;if device not busy -> done \n\t"
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" brne _Li2c_start_wait_done \n\t"
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" rcall ass_i2c_stop ;terminate write & enable IRQ \n\t"
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" rjmp _Li2c_start_wait1 ;device busy, poll ack again \n\t"
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"_Li2c_start_wait_done: \n\t"
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" pop __tmp_reg__ ;pop off orig argument \n\t"
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" ret "
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: : [SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN),
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[SCLIN] "I" (SCL_IN),[SCLPIN] "I" (SCL_PIN));
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}
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void i2c_stop(void)
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{
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__asm__ __volatile__
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(
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" sbi %[SCLDDR],%[SCLPIN] ;force SCL low \n\t"
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" sbi %[SDADDR],%[SDAPIN] ;force SDA low \n\t"
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" rcall ass_i2c_delay_half ;T/2 delay \n\t"
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" cbi %[SCLDDR],%[SCLPIN] ;release SCL \n\t"
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" rcall ass_i2c_delay_half ;T/2 delay \n\t"
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" sbis %[SCLIN],%[SCLPIN] ;check for clock stretching slave\n\t"
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" rcall ass_i2c_wait_scl_high ;wait until SCL=H\n\t"
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" cbi %[SDADDR],%[SDAPIN] ;release SDA \n\t"
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" rcall ass_i2c_delay_half \n\t"
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#if I2C_NOINTERRUPT
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" sei ;enable interrupts again!\n\t"
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#endif
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: : [SCLDDR] "I" (SCL_DDR), [SCLPIN] "I" (SCL_PIN), [SCLIN] "I" (SCL_IN),
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[SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN));
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}
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bool i2c_write(uint8_t value)
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{
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__asm__ __volatile__
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(
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" sec ;set carry flag \n\t"
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" rol r24 ;shift in carry and shift out MSB \n\t"
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" rjmp _Li2c_write_first \n\t"
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"_Li2c_write_bit:\n\t"
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" lsl r24 ;left shift into carry ;; 1C\n\t"
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"_Li2c_write_first:\n\t"
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" breq _Li2c_get_ack ;jump if TXreg is empty;; +1 = 2C \n\t"
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" sbi %[SCLDDR],%[SCLPIN] ;force SCL low ;; +2 = 4C \n\t"
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" nop \n\t"
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" nop \n\t"
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" nop \n\t"
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" brcc _Li2c_write_low ;;+1/+2=5/6C\n\t"
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" nop ;; +1 = 7C \n\t"
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" cbi %[SDADDR],%[SDAPIN] ;release SDA ;; +2 = 9C \n\t"
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" rjmp _Li2c_write_high ;; +2 = 11C \n\t"
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"_Li2c_write_low: \n\t"
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" sbi %[SDADDR],%[SDAPIN] ;force SDA low ;; +2 = 9C \n\t"
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" rjmp _Li2c_write_high ;;+2 = 11C \n\t"
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"_Li2c_write_high: \n\t"
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#if I2C_DELAY_COUNTER >= 1
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" rcall ass_i2c_delay_half ;delay T/2 ;;+X = 11C+X\n\t"
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#endif
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" cbi %[SCLDDR],%[SCLPIN] ;release SCL ;;+2 = 13C+X\n\t"
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" cln ;clear N-bit ;;+1 = 14C+X\n\t"
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|
" nop \n\t"
|
|
" nop \n\t"
|
|
" nop \n\t"
|
|
" sbis %[SCLIN],%[SCLPIN] ;check for SCL high ;;+2 = 16C+X\n\t"
|
|
" rcall ass_i2c_wait_scl_high \n\t"
|
|
" brpl _Ldelay_scl_high ;;+2 = 18C+X\n\t"
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"_Li2c_write_return_false: \n\t"
|
|
" clr r24 ; return false because of timeout \n\t"
|
|
" rjmp _Li2c_write_return \n\t"
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"_Ldelay_scl_high: \n\t"
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#if I2C_DELAY_COUNTER >= 1
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|
" rcall ass_i2c_delay_half ;delay T/2 ;;+X= 18C+2X\n\t"
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|
#endif
|
|
" rjmp _Li2c_write_bit \n\t"
|
|
" ;; +2 = 20C +2X for one bit-loop \n\t"
|
|
"_Li2c_get_ack: \n\t"
|
|
" sbi %[SCLDDR],%[SCLPIN] ;force SCL low ;; +2 = 5C \n\t"
|
|
" nop \n\t"
|
|
" nop \n\t"
|
|
" cbi %[SDADDR],%[SDAPIN] ;release SDA ;;+2 = 7C \n\t"
|
|
#if I2C_DELAY_COUNTER >= 1
|
|
" rcall ass_i2c_delay_half ;delay T/2 ;; +X = 7C+X \n\t"
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|
#endif
|
|
" clr r25 ;; 17C+2X \n\t"
|
|
" clr r24 ;return 0 ;; 14C + X \n\t"
|
|
" cbi %[SCLDDR],%[SCLPIN] ;release SCL ;; +2 = 9C+X\n\t"
|
|
"_Li2c_ack_wait: \n\t"
|
|
" cln ; clear N-bit ;; 10C + X\n\t"
|
|
" nop \n\t"
|
|
" sbis %[SCLIN],%[SCLPIN] ;wait SCL high ;; 12C + X \n\t"
|
|
" rcall ass_i2c_wait_scl_high \n\t"
|
|
" brmi _Li2c_write_return_false ;; 13C + X \n\t "
|
|
" sbis %[SDAIN],%[SDAPIN] ;if SDA hi -> return 0 ;; 15C + X \n\t"
|
|
" ldi r24,1 ;return true ;; 16C + X \n\t"
|
|
#if I2C_DELAY_COUNTER >= 1
|
|
" rcall ass_i2c_delay_half ;delay T/2 ;; 16C + 2X \n\t"
|
|
#endif
|
|
"_Li2c_write_return: \n\t"
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
" sbi %[SCLDDR],%[SCLPIN] ;force SCL low so SCL=H is short\n\t"
|
|
" ret \n\t"
|
|
" ;; + 4 = 17C + 2X for acknowldge bit"
|
|
::
|
|
[SCLDDR] "I" (SCL_DDR), [SCLPIN] "I" (SCL_PIN), [SCLIN] "I" (SCL_IN),
|
|
[SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN), [SDAIN] "I" (SDA_IN));
|
|
return true; // fooling the compiler
|
|
}
|
|
|
|
uint8_t i2c_read(bool last)
|
|
{
|
|
__asm__ __volatile__
|
|
(
|
|
" ldi r23,0x01 \n\t"
|
|
"_Li2c_read_bit: \n\t"
|
|
" sbi %[SCLDDR],%[SCLPIN] ;force SCL low ;; 2C \n\t"
|
|
" cbi %[SDADDR],%[SDAPIN] ;release SDA(prev. ACK);; 4C \n\t"
|
|
" nop \n\t"
|
|
" nop \n\t"
|
|
" nop \n\t"
|
|
#if I2C_DELAY_COUNTER >= 1
|
|
" rcall ass_i2c_delay_half ;delay T/2 ;; 4C+X \n\t"
|
|
#endif
|
|
" cbi %[SCLDDR],%[SCLPIN] ;release SCL ;; 6C + X \n\t"
|
|
#if I2C_DELAY_COUNTER >= 1
|
|
" rcall ass_i2c_delay_half ;delay T/2 ;; 6C + 2X \n\t"
|
|
#endif
|
|
" cln ; clear N-bit ;; 7C + 2X \n\t"
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
" sbis %[SCLIN], %[SCLPIN] ;check for SCL high ;; 9C +2X \n\t"
|
|
" rcall ass_i2c_wait_scl_high \n\t"
|
|
" brmi _Li2c_read_return ;return if timeout ;; 10C + 2X\n\t"
|
|
" clc ;clear carry flag ;; 11C + 2X\n\t"
|
|
" sbic %[SDAIN],%[SDAPIN] ;if SDA is high ;; 11C + 2X\n\t"
|
|
" sec ;set carry flag ;; 12C + 2X\n\t"
|
|
" rol r23 ;store bit ;; 13C + 2X\n\t"
|
|
" brcc _Li2c_read_bit ;while receiv reg not full \n\t"
|
|
" ;; 15C + 2X for one bit loop \n\t"
|
|
|
|
"_Li2c_put_ack: \n\t"
|
|
" sbi %[SCLDDR],%[SCLPIN] ;force SCL low ;; 2C \n\t"
|
|
" cpi r24,0 ;; 3C \n\t"
|
|
" breq _Li2c_put_ack_low ;if (ack=0) ;; 5C \n\t"
|
|
" cbi %[SDADDR],%[SDAPIN] ;release SDA \n\t"
|
|
" rjmp _Li2c_put_ack_high \n\t"
|
|
"_Li2c_put_ack_low: ;else \n\t"
|
|
" sbi %[SDADDR],%[SDAPIN] ;force SDA low ;; 7C \n\t"
|
|
"_Li2c_put_ack_high: \n\t"
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
#if I2C_DELAY_COUNTER >= 1
|
|
" rcall ass_i2c_delay_half ;delay T/2 ;; 7C + X \n\t"
|
|
#endif
|
|
" cbi %[SCLDDR],%[SCLPIN] ;release SCL ;; 9C +X \n\t"
|
|
" cln ;clear N ;; +1 = 10C\n\t"
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
" sbis %[SCLIN],%[SCLPIN] ;wait SCL high ;; 12C + X\n\t"
|
|
" rcall ass_i2c_wait_scl_high \n\t"
|
|
#if I2C_DELAY_COUNTER >= 1
|
|
" rcall ass_i2c_delay_half ;delay T/2 ;; 11C + 2X\n\t"
|
|
#endif
|
|
"_Li2c_read_return: \n\t"
|
|
" nop \n\t "
|
|
" nop \n\t "
|
|
"sbi %[SCLDDR],%[SCLPIN] ;force SCL low so SCL=H is short\n\t"
|
|
" mov r24,r23 ;; 12C + 2X \n\t"
|
|
" clr r25 ;; 13 C + 2X\n\t"
|
|
" ret ;; 17C + X"
|
|
::
|
|
[SCLDDR] "I" (SCL_DDR), [SCLPIN] "I" (SCL_PIN), [SCLIN] "I" (SCL_IN),
|
|
[SDADDR] "I" (SDA_DDR), [SDAPIN] "I" (SDA_PIN), [SDAIN] "I" (SDA_IN)
|
|
);
|
|
return ' '; // fool the compiler!
|
|
}
|
|
|
|
#else
|
|
#error "ONLY SUPPORTED ON AVR PROCESSORS"
|
|
#endif // defined (__AVR__)
|
|
|
|
#endif
|
|
|
|
|
|
|